The present invention relates to medical nebulising apparatus for inhalatory use. In this specification, the term "nebulisation" is intended to include the formation of a spray from a powder as well as from a liquid.
In the medical field, the inhalation of nebulised drugs is an accepted way of treating various medical conditions such as asthma, bronchitis, cystic fibrosis and other conditions of the respiratory tract. Existing medical nebulisers are not easy to use by all patients. They are expensive, bulky and require a separate compressed air or oxygen supply, e.g. from a compressed air container or from an electric compressor device. A patient, therefore, is unlikely to have or carry his own nebuliser and has to visit a hospital for inhalation treatment.
It has been proposed to use a rotatable disc for dispersing particles in a medical nebuliser. The material is fed in an axial direction onto the disc to disperse the particles in a large chamber and an airstream is independently generated to carry particles out of the chamber. There is, therefore, a generation of a large proportion of large particles and the apparatus is massive.
One common way of producing a spray is by the use of a pressurised can, commonly used, for example, for such purposes as paint spraying, air fresheners and insecticide sprays. Although these cans are readily portable and are used as inhalation devices, they suffer several drawbacks. They require a pressurised carrier gas, which itself is undesirable for environmental reasons and the pressure is excessively high, with the result that the spray particles impact in the mouth and coalesce. The devices are not re-usable and they need a very high degree of coordination and effort by the patient.